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mirror of https://github.com/systemd/systemd-stable.git synced 2024-10-31 07:51:08 +03:00
systemd-stable/udev.c
kay.sievers@vrfy.org 7e89a569cc [PATCH] prevent deadlocks on an corrupt udev database
Here is the patch, that should prevent all of the known deadlocks with
corrupt tdb databases we discovered.
Thanks to Frank Steiner <fsteiner-mail@bio.ifi.lmu.de>, who tested all this
endlessly with a NFS mounted /dev. The conclusion is, that udev will not work
on filesystems without proper record locking, but we should prevent the
endless loops anyway. This patch implements:

o recovery from a corrupted udev database. udev will continue
  without database support now, instead of doing nothing. So the node should
  be generated in any case, remove will obviously not work for custom names.

o added iteration limits to the tdb-code at the places we discovered endless
  loops. In the case tdb tries to find more than 100.000 entries with the
  same hash, we better give up :)

o prevent a {all_partitions} loop caused by corrupt db data

o log all tdb errors to syslog

o switch sleep() to usleep() cause we want to use alarm()
2005-04-26 21:47:44 -07:00

193 lines
3.9 KiB
C

/*
* udev.c
*
* Userspace devfs
*
* Copyright (C) 2003,2004 Greg Kroah-Hartman <greg@kroah.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation version 2 of the License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <signal.h>
#include "libsysfs/sysfs/libsysfs.h"
#include "udev.h"
#include "udev_lib.h"
#include "udev_version.h"
#include "logging.h"
#include "namedev.h"
#include "udevdb.h"
/* timeout flag for udevdb */
extern sig_atomic_t gotalarm;
/* global variables */
char **main_argv;
char **main_envp;
#ifdef LOG
unsigned char logname[LOGNAME_SIZE];
void log_message(int level, const char *format, ...)
{
va_list args;
if (!udev_log)
return;
va_start(args, format);
vsyslog(level, format, args);
va_end(args);
}
#endif
asmlinkage static void sig_handler(int signum)
{
switch (signum) {
case SIGALRM:
gotalarm = 1;
info("error: timeout reached, event probably not handled correctly");
break;
case SIGINT:
case SIGTERM:
udevdb_exit();
exit(20 + signum);
default:
dbg("unhandled signal %d", signum);
}
}
static char *subsystem_blacklist[] = {
"scsi_host",
"scsi_device",
"usb_host",
"pci_bus",
"pcmcia_socket",
""
};
int main(int argc, char *argv[], char *envp[])
{
main_argv = argv;
main_envp = envp;
struct sigaction act;
char *action;
char *devpath = "";
char *subsystem = "";
int i;
int retval = -EINVAL;
enum {
ADD,
REMOVE,
UDEVSTART,
} act_type;
dbg("version %s", UDEV_VERSION);
init_logging("udev");
udev_init_config();
if (strstr(argv[0], "udevstart")) {
act_type = UDEVSTART;
} else {
action = get_action();
if (!action) {
dbg("no action?");
goto exit;
}
if (strcmp(action, "add") == 0) {
act_type = ADD;
} else if (strcmp(action, "remove") == 0) {
act_type = REMOVE;
} else {
dbg("unknown action '%s'", action);
goto exit;
}
devpath = get_devpath();
if (!devpath) {
dbg("no devpath?");
goto exit;
}
dbg("looking at '%s'", devpath);
/* we only care about class devices and block stuff */
if (!strstr(devpath, "class") && !strstr(devpath, "block")) {
dbg("not a block or class device");
goto exit;
}
subsystem = get_subsystem(main_argv[1]);
if (!subsystem) {
dbg("no subsystem?");
goto exit;
}
/* skip blacklisted subsystems */
i = 0;
while (subsystem_blacklist[i][0] != '\0') {
if (strcmp(subsystem, subsystem_blacklist[i]) == 0) {
dbg("don't care about '%s' devices", subsystem);
goto exit;
}
i++;
}
}
/* set signal handlers */
act.sa_handler = sig_handler;
sigemptyset (&act.sa_mask);
/* alarm must interrupt syscalls*/
sigaction(SIGALRM, &act, NULL);
sigaction(SIGINT, &act, NULL);
sigaction(SIGTERM, &act, NULL);
/* trigger timout to interrupt blocking syscalls */
alarm(ALARM_TIMEOUT);
/* initialize udev database */
if (udevdb_init(UDEVDB_DEFAULT) != 0)
info("error: unable to initialize database, continuing without database");
switch(act_type) {
case UDEVSTART:
dbg("udevstart");
namedev_init();
udev_sleep = 0;
retval = udev_start();
break;
case ADD:
dbg("udev add");
namedev_init();
retval = udev_add_device(devpath, subsystem, NOFAKE);
break;
case REMOVE:
dbg("udev remove");
retval = udev_remove_device(devpath, subsystem);
}
udevdb_exit();
exit:
return retval;
}